Armadillosuchus Arrudai (Ancient animal) Saltwater Crocodile
Ancient crocodile fossil in Brazil. Source:
Ancient crocodile fossil in Brazil. Source:
Name Origin:
The genus name, Armadillosuchus means "armadillo crocodile".

The Armadillosuchus Arrudai was an animal that had features of both a crocodile and an armadillo. It had the body and head of a crocodile and the arms and hands of an armadillo. This fossil was discovered in 2005 in Brazil by paleontologists but had only been described and identified in February 2009. Research have said that the fossil of the "armadillo-like crocodile" lived around the late Cretaceous period in Brazil about 90 million years ago. The fossil was measured 2 metres in length and weighed about 120 kilograms. Similarly to the saltwater crocodile, the fossil has a large head but with a much narrower snout. It has a unique armoured back that has not been found in any other species before.

São Paolo, Brazil. Source:
São Paolo, Brazil. Source:

This fossil lived in only the Bauru region of São Paolo state in Brazil. The place was considered arid at that time and it was where the Armadillosuchus Arrudai was the only 'crocodile' that roamed around the area.

The living conditions of the were different from saltwater crocodiles. They lived in hot and dry climates where it rained quite often. This area was where not one where waters and rivers were permanent like where the crocodiles live today. There were seasonal rainfalls and flash floods occured quite often. Not many modern crocodiles would be found today living around these areas.
Armadillosuchus Arrudai roaming on land. Source:
Armadillosuchus Arrudai roaming on land. Source:

The Armadillosuchus Arrudai lived during the time of dinosaurs, the time of the Cretaceous preiod. The temperature was mostly around 45 degrees Celsius during the Cretaceous period. The climate was always very warm and there was a high sea level. The Cretaceous period began with a lot of new species of animals to the Earth and it ended with a lot of them including the dinosaurs and marine reptiles becoming extinct.

Scientific Classification:

Labelled Diagram of Armadillosuchus Arrudai:
Labelled Diagram of Armadillosuchus Arrudai. Image from:

Structual Adaptation 1:
Legs of an Armadillosuchus Arrudai
The Armadillosuchus Arrudai has legs longer than a saltwater crocodile. These legs lift the Armadillosuchus Arrudai 's body off the ground unlike the legs of a modern crocodile which do not lift the body up. This was because the Armadillosuchus Arrudai was a an animal. This arrangement is built differently from a modern crocodile as this animal probably had to run away from predators because at the time when they lived was the time when dinosaurs roamed the earth so there could have been several species that were big predators such as the T-rex. At that time there were a lot chasing going on so most animals had long legs for running. The environmental pressure that may have led to the long legs is that the Armadillosuchus Arrudai lived surrounded by animals that ran around chasing each other.

Structural Adaptation 2: Bony Plate Armour
Armadillosuchus Arrudai skeleton structure. Source:
Armadillosuchus Arrudai skeleton structure. Source:
The most unique feature of this fossil is the heavy, bony plate armour that has not been found in any other animal speices. It is usually compared to the bony plates of an armadillo. These plates are rigid shields and have flexible bands that covers its back. The Armadillosuchus Arrudai also had bony plates in the shape of hexagons on the back of its head. This enabled the neck to move so that it was not always faced in one direction as its head is strangely positioned to the left. Underneath this shield of hexagonal plates, there are a series of mobile-banded body armour. This interested scientists because mobile armoured bands were like those of the armadillo. Because of it being the only crocodilyform with mobile-banded body armour, the Armadillosuchus Arrudai probably did not have any predators.

Behavioural Adaptation 1: Digs Like an Armadillo
The Armadillosuchus Arrudai was an unusal reptile that lived by digging. The large claws or the arms and legs of the Armadillosuchus Arrudai are similar to those of an armadillo's. It is said that the arms were used for digging in the soil. This was for the purpose of avoiding dehydration in the arid environment it lived in. They may have eaten food from underground so they had to use their claws to dig the soil. This is similar to the way armadillos search for food.

Behavioural Adaptation 2: Eats Like a Mammal
The jaw of the Armadillosuchus Arrudai. Source:
The jaw of the Armadillosuchus Arrudai. Source:

The Armadillosuchus Arrudai had a rather narrow snout and a row of different sized teeth in its mouth and unlike the saltwater crocodile, or any other crocodile living today, they ate mostly roots, pine branches, mollusks and dried meat. The Armadillosuchus Arrudai had large canine teeth that showed when the jaw was shut and many other smaller teeth. Scientists have come to the conlusion that this fossil chewed by moving its lower jaw forwards and backwards making their teeth tear into the food instead of powerfully clamping it like a normal crocodile today would do. Scientists describe that they ate and chewed like mammals and humans do because according to the genus name, Armadillosuchus, it was an omnivore. This ancient creature lived in an environment that was dry and hot so the majority of food available to them would be those such as plants, seafood, etc. not the large land animals that saltwater crocodiles catch nowadays.

Physiological Adaptation: Strong Heart
The heart of the Armadillosuchus Arrudai was strong as it had to be living on the land. Land living animals are more active than marine animals and unlike the crocodiles nowadays, they had to run around because of being chased and they would waste a lot of energy doing that. The Armadillosuchus Arrudai does not get as tired easily as saltwater crocodiles because they do not feel great exhaustion after attacking on prey or another crocodile. Although this is the case, their hearts work harder to be able to live in its environment with wild land animals.

Extinction Pressure:
The Armadillosuchus Arrudai was one of the many new species of animals that appeared in the Cretaceous period and ended in the Cretaceous period. The main reason that might have led it to its extinction was because during the time of the late Cretaceous period, many species especially dinosaurs, pterosaurs and marine reptiles such as the Armadillosuchus Arrudai were disappearing with the mass extinction due to a big change in climate. This was called a mass extinction. It is thought that the great change in climate was because of the continental drift, a drop in the sea level which may have led the rising of land, extreme difference in temperature in continents above and below the equator and increase in seasonality. There were diseases going around at that time that may have affected the extinction and the mammals that ate eggs of the reptiles like the Armadillosuchus Arrudai. Then there are the theories of an aesteroid hitting up on Earth causing all the species to disappear all at one, the high volcanism theory and many others. The Cretaceous period was also the time when the Earth's continents started to break apart from the one Pangaea and change into the form of today. The Armadillosuchus Arrudai became extinct because it lived in the time when massive changes occured including extinction of new species, dramatic climate changes and the formation of new continents.